ANDROID: sched: Export symbols for vendor modules

Export sysctl_sched_min_granularity and
sysctl_sched_idle_min_granularity. In the vendor module, it will use
several static function in GKI, while we do not want to export these
static functions, which will need to make them not static, we copied
them to the vendor module, so we need the export the symbols used in
those static functions. For example, sysctl_sched_min_granularity
and sysctl_sched_idle_min_granularity are referred in sched_slice(),
and they are only used as read-only.

Bug: 316276520
Change-Id: I976d0a1f3a70e8e60099e55fdd3cc99a90053fbb
Signed-off-by: Rick Yiu <rickyiu@google.com>